Pacemaker Electrocardiography of Rate Smoothing During DDD Pacing

A rate smoothing option is available in a new bipolar AV universal (DDD) pacemaker. In three patients, two with intact retrograde conduction and one with retrograde block, rate smoothing values of 3% and 6% were programmed. Irregular pacemaker-mediated tachycardia occurred in one patient and AV synchrony was temporarily lost in the other two patients. In this report, we describe the pacemaker electrocardiography of rate smoothing during DDD pacing.     

A single‐index threshold Cox proportional hazard model for identifying a treatment‐sensitive subset based on multiple biomarkers

In this paper, we introduce a single‐index threshold Cox proportional hazard model to select and combine biomarkers to identify patients who may be sensitive to a specific treatment. A penalized smoothed partial likelihood is proposed to estimate the parameters in the model. A simple, efficient, and unified algorithm is presented to maximize this likelihood function. The estimators based on this likelihood function are shown to be consistent and asymptotically normal. Under mild conditions, the proposed estimators also achieve the oracle property. The proposed approach is evaluated through simulation analyses and application to the analysis of data from two clinical trials, one involving patients with locally advanced or metastatic pancreatic cancer and one involving patients with resectable lung cancer.     

指数平滑法在麻疹发病率预测中的应用

目的 通过指数平滑法对麻疹发病率进行预测,为制订预防和控制麻疹的流行提供依据。 方法 收集2005-2015年某区确诊的麻疹发病率,通过SPSS 18.0进行指数平滑法预测,并对预测结果进行评价。 结果 指数平滑法的Holt-Winters相乘模型适合麻疹月发病率的预测(RMSE=7.69,adj R²=0.52, R²=0.85, Ljung-Box Q=21.91),预测模型线性趋势Alpha=1.000,P=0.000。模型预测结果显示2015年的麻疹疫情处于相对低发水平,麻疹月发病率将呈上升后波动趋势,实际麻疹月发病率则出现先上升后急剧下降维持在低水平上的波动趋势。 结论 指数平滑模型1～5月份预测结果与实际发病率的相对误差仅为10.60%,说明指数平滑法在短期预测麻疹发病情况中有一定效果。     

Induced smoothing for rank‐based regression with recurrent gap time data

Various semiparametric regression models have recently been proposed for the analysis of gap times between consecutive recurrent events. Among them, the semiparametric accelerated failure time (AFT) model is especially appealing owing to its direct interpretation of covariate effects on the gap times. In general, estimation of the semiparametric AFT model is challenging because the rank‐based estimating function is a nonsmooth step function. As a result, solutions to the estimating equations do not necessarily exist. Moreover, the popular resampling‐based variance estimation for the AFT model requires solving rank‐based estimating equations repeatedly and hence can be computationally cumbersome and unstable. In this paper, we extend the induced smoothing approach to the AFT model for recurrent gap time data. Our proposed smooth estimating function permits the application of standard numerical methods for both the regression coefficients estimation and the standard error estimation. Large‐sample properties and an asymptotic variance estimator are provided for the proposed method. Simulation studies show that the proposed method outperforms the existing nonsmooth rank‐based estimating function methods in both point estimation and variance estimation. The proposed method is applied to the data analysis of repeated hospitalizations for patients in the Danish Psychiatric Center Register.     

Self‐controlled case series method with smooth age effect

The self‐controlled case series method, commonly used to investigate potential associations between vaccines and adverse events, requires information on cases only and automatically controls all age‐independent multiplicative confounders while allowing for an age‐dependent baseline incidence. In the parametric version of the method, we modelled the age‐specific relative incidence by using a piecewise constant function, whereas in the semiparametric version, we left it unspecified. However, mis‐specification of age groups in the parametric version can lead to biassed estimates of exposure effect, and the semiparametric approach runs into computational problems when the number of cases in the study is moderately large. We, thus, propose to use a penalized likelihood approach where the age effect is modelled using splines. We use a linear combination of cubic M‐splines to approximate the age‐specific relative incidence and integrated splines for the cumulative relative incidence. We conducted a simulation study to evaluate the performance of the new approach and its efficiency relative to the parametric and semiparametric approaches. Results show that the new approach performs equivalently to the existing methods when the sample size is small and works well for large data sets. We applied the new spline‐based approach to data on febrile convulsions and paediatric vaccines. Copyright © 2013 John Wiley & Sons, Ltd.     

补肾疏肝法在月经病中的应用

月经病是妇科的常见病,中医临证讲究治病求本,审因论治。肝肾对月经的调节起着至关重要的作用,肾为元阴元阳之所处,而女子更以血为本,肝为先天,故在治疗月经病时多从肝肾论治,只有肾精充盛,肝气调达,方能血海充盈,经候如期。故该文针对补肾疏肝法在月经病中的应用做了进一步的阐述。     

中西医结合治疗输卵管阻塞性不孕症64例

目的：观察中西医结合治疗输卵管阻塞性不孕症的临床疗效。方法：将128例患者按照随机数字表法分为观察组和对照组．每组各64例。对照组采用输卵管通液术等常规西医处理,观察组在对照组的基础上加用中药清热化湿疏肝活血方加减治疗。结果：观察组有效率为89．06％,对照组有效率为62．50％,两组有效率比较,差异有统计学意义（P〈0．05）。观察组妊娠率为42．19％;对照组妊娠率为26．56％;两组妊娠率比较,差异有统计学意义（P〈0．05）。两组患者治疗期间均未见明显不良反应。结论：中西医结合治疗输卵管阻塞性不孕症,临床疗效安全可靠。     

On model specification and selection of the Cox proportional hazards model

Prognosis plays a pivotal role in patient management and trial design. A useful prognostic model should correctly identify important risk factors and estimate their effects. In this article, we discuss several challenges in selecting prognostic factors and estimating their effects using the Cox proportional hazards model. Although a flexible semiparametric form, the Cox's model is not entirely exempt from model misspecification. To minimize possible misspecification, instead of imposing traditional linear assumption, flexible modeling techniques have been proposed to accommodate the nonlinear effect. We first review several existing nonparametric estimation and selection procedures and then present a numerical study to compare the performance between parametric and nonparametric procedures. We demonstrate the impact of model misspecification on variable selection and model prediction using a simulation study and an example from a phase III trial in prostate cancer. Copyright © 2013 John Wiley & Sons, Ltd.